1. Field of the Invention
This invention relates to a display apparatus designed to operate in a power-saving fashion that is adapted to the input image signal.
2. Related Background Art
Known power-saving techniques for display apparatus include DPMS (Display Power Management Signaling) of the VESA (Video Electronics Standard Association). In projectors using image display devices, the light source lamp is normally turned off if no input signal has been received for a certain period of time.
In some display apparatus for video cam coders, the image being displayed is blacked out if no keys have been operated for a certain period of time.
As a result of the recent development of multi-media communication systems, there is a strong demand for display apparatus having a large and bright display screen and compatible with various input signals including NTSC signals and other television signals as well as image signals from computers. Metal halide lamps having a high output power and high pressure mercury lamps are being popularly used for large and bright display screens. Although power is reliably saved by turning off the light source lamp, it takes a considerable time for such a lamp to restore the proper brightness after it is turned on once again. Of the display apparatus compatible with various input signals, some meet the power-saving standards such as DPMS for signals from personal computers while the others do not. Additionally, no power-saving standards are currently provided for television signals and it is not possible for display apparatus to effectively meet the requirement of power-saving by a single operation such as turning off the light source lamp.